Field of Invention
The present invention is related to a semiconductor device and a method of forming the same, and more generally to a memory device and a method of forming the same.
Description of Related Art
With the development of a multi-functional chip, integrating elements with different functions, e.g., a memory and a metal-oxide-semiconductor (MOS) transistor, into the same chip has become the mainstream in the market. However, the process for fabricating a memory is commonly separated from the process for fabricating a MOS transistor. Hence, multiple photo-masks and complicated process steps are required, so as to increase the process cost and weaken the competitiveness. Therefore, how to effectively integrate a memory and a MOS transistor has been drawn high attention in the industry.